Conventionally, the growth of algae and other undesirable microorganisms in swimming pool waters has been suppressed by the use of halogen-based chemical additives. In particular, liquid or solid forms of chlorine-containing chemicals such as hypochlorous acid, hypochlorite salts, sodium dichloro-s-triazinetrione (dichlor), and trichloro-s-triazinetrione (trichlor) have been added to swimming pool waters as algaecides. While effective in reducing or preventing algae growth, these additives are lost relatively quickly due to evaporation and photo-degradation, i.e, light-induced decomposition. Moreover, chlorine-containing additives are typically corrosive to steel surfaces and may also be an irritant to the skin and eyes. Accordingly, it is desirable to use alternative swimming pool treatment chemicals in order to reduce or eliminate the need for treatment chemicals containing chlorine or other halogens as well as to mitigate some of the negative attributes of chlorine and other halogen pool chemicals.
Attempts have been made to use boron-containing chemicals, such as tetraborate salts (i.e., borax) and boric acid as alternative swimming pool treatment chemicals. However, these chemicals are problematic. They tend to form into solid blocks or lumps when contacted with water which sink to the bottom of a pool due to the relatively limited solubility of the chemicals, or they tend to float on top of the water and are aesthetically displeasing. Crusts or scaling may also form on the interior surfaces of the swimming pool as well. Further, boric acid is also corrosive to metal fixtures and fittings.
In addition, the use of boric acid in swimming pools has been found to promote the formation of hypochlorous acid, which is an eye irritant, if used in conjunction with chlorine-based treatment chemicals. Borax also exhibits problems with chlorine retention as it promotes the photo-degradation of sodium dichloro-s-triazinetrione (i.e., dichlor) when the two chemicals are used together to treat pool water.
Thus, there remains a continuing need for improved alternative swimming pool treatment chemicals.